[SystemZ][z/OS] Add back removed AutoConvert.h headers that were incorrectly identified as unused to fix a build error on z/OS

Author: abhina-sree

llvm/lib/Support/InitLLVM.cpp

@@ -8,6 +8,7 @@
 
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/AutoConvert.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ManagedStatic.h"

llvm/lib/Support/raw_ostream.cpp

@@ -13,6 +13,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Config/config.h"
+#include "llvm/Support/AutoConvert.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Duration.h"
 #include "llvm/Support/ErrorHandling.h"